KV6 overheating and losing coolant

[ricebridge]

Originally Posted by Comfortably Numb

I know nothing about V6s. But other cars I have owned that started to overheat with hills, towing, fast driving or other minor extra loading, 2 turned out to be worn/corroded pump impellor and/or bearings - the giveaway being water dripping from the pump when first started, before it got hot, when it just evaporated invisibly.

When you say "bearings", do you mean the water pump bearings, or engine bearings?

Originally Posted by Comfortably Numb

And one other - radiator was half sludged up. What miles has your car done?

I just flushed out the radiator with water from my garden hose yesterday, and it seemed to flow decently. But if it were sludged up, wouldn't that have impaired the water flow when I flushed it out?

The car has done a bit over 200,000 kms.

Originally Posted by Comfortably Numb

Many recommend changing the coolant pump with the timing belts, every time.

Yes indeed, that's probably a must. I'm quite sure that was done last time there was a timing belt change on this car, some 3,000 kms ago. But that obviously doesn't mean that the one they put in was top-quality...

Timing belt change always seems to me as easy as performing a quadruple bypass operation on myself in front of the mirror, so I'm shying away from it, but perhaps it could be worth it within not too soon after all?

[Comfortably Numb]

Just read another post (Robti) saying how inaccessible the pump is on these. Is there an east way of checking if your rad is sludged up/less than efficient. Is there an easily accessible hose on these that could be pulled off on cold tickover for a few seconds to ascertain flow rate?

[StewartIngram]

it now seems that a previous owner has taken the hose that is supposed to go from the engine to the heater, extended it ad nauseam, and drawn it to the front of the car. Where it has then been connected to the hose coming out from the heater...


For what it is worth, I've done a similar extension on mine! (Actually on the previous gold KV6, for about 9 years, then transferred over to the present blue KV6 nearly a year ago).
Basically no problems, but a pig to bleed. Even doing it the Rover way is not always successful, as the extended hose highest point is near the o/s suspension strut mounting. Vacuum filling works best I find. As for Haynes manual, no idea, as someone else on here says, best use for them is under the jack as a pad.
And the reason for extending my hose? (I nearly forgot). I have converted to lpg, and the vapouriser (which needs a hot water feed) is mounted in the engine bay, adjacent to that o/s strut. When I got the blue car, I had to change the thermostat. Just recently, possibly even soon after changing the thermostat, I had a small water loss. This developed into a cycle of little loss for a few days, followed by a pool of water underneath the car. Topping up made it ok again for a few days. It was very difficult to see in the V of the engine (more lpg stuff in the way) but I did notice some coolant there. I can only think that the small leakage was consistent, filing up the V to a certain level, which then overflowed and drained to the floor? I then read on here about the O-rings on the thermostat reacting with the plastic body, deforming to a square cross section and causing a leak. So, I bit the bullet and ordered new ones. Removal of the manifold found a lot of water which I removed. (Incidentally just prior to this, I had done the cambelts, changing the water pump at the same time - it didn't appear to have any leaks). Anyway, old O-rings were now square section, new ones circular. With everything refitted, I have had no leaks (about a month). I'm still suffering a little with what I believe to be an airlock near the vapouriser though, I will have to try vacuum fill again. I'm also seriously thing of a bit of copper central heating plumbing around that area, incorporating a bleed valve as it is the highest point!

Stewart

[ricebridge]

Thanks Stewart. So the changes on my car could have been an unfinished LPG project? The car came without top or bottom engine covers, which has also made me suspect someone just giving up halfway through something.

[ricebridge]

Still leaks.
Narrowed it down to a leak somewhere but can’t figure out where, and I need some help to think.

Done so far:
* Dismantled most of the cooling system.
* Flushed out the entire cooling system with garden hose. Paid special attention in that respect to radiator, oil cooler, and heater matrix.
* Rebuilt the entire cooling system back to original.
* Used jubilees wherever I could.
* Had to use non-standard hoses in some places, due to lack of original spares.
* Bled the system very carefully.
* Replaced expansion tank cap with brand new one.
* Changed oil for good measure.

Moreover:
* Water pump and thermostat were replaced some 2,000 kms ago by MG Rover garage.
* Cylinder head inspected, inlet manifold gasket replaced at that same occasion.
* No visible coolant in V.
* Plenty of dripping coolant on left side of CAR as seen from the driver's position, underneath; could either indicate leak or just spilling from bleeding/topping up.
* Small spray drops on top of engine fuse box from direction of expansion tank cap.
* No mayo in oil or engine.
* Some white smoke on cold startup (ambient temp 0 to +6C), but none visible when reaching operating temp.

Possible faults:
* Me failing to tighten jubilee clips enough.
* Faulty original clips somewhere.
* Faulty installation of water pump.
* Faulty installation of thermostat.
* Thermostat or water pump breaking after 2,000 kms.
* Leaking radiator (how did that happen?!)
* HGF.

But as I said, I need some help to think now.
Any other possible causes?
Am I missing something?
Which causes are the most plausible?

[Lord of Hog]

The radiator is prone to failure where the plastic elbows attach to the metal structure. It's a lot more common than you might think and surprisingly hard to detect if you're not specifically looking for it.

[SD1too]

Originally Posted by ricebridge

Plenty of dripping coolant on left side of engine, underneath; could either indicate leak or just spilling from bleeding/topping up.

Jonathan, can you specify what you mean by the left side of the engine please? On a transverse V6 this is the outer side of the left hand bank facing the radiator, but many people stand at the open bonnet and use the engine bay geography to describe it.

Small spray drops on top of engine fuse box from direction of expansion tank cap.

Is that definitely coolant, i.e. is antifreeze residue present when dry? Is it happening repeatedly? What's the maximum coolant temperature now when the engine is under load?

Some white smoke on cold startup (ambient temp 0 to +6C)

That could be condensation in the exhaust being heated to vapour.

Simon

[Randyjim]

Originally Posted by ricebridge

Possible faults:
* Thermostat or water pump breaking after 2,000 kms.

My last OEM water pump lasted just 500 miles (800km). Coolant was pouring out from the area around the crank pulley. I believe there has been an issue with a change in suppliers to Xpart. Do you know what the brand on the pump was? More than one type are being supplied in X-part boxes, at least they were 12-18 months ago.

[ricebridge]

Originally Posted by Lord of Hog

The radiator is prone to failure where the plastic elbows attach to the metal structure. It's a lot more common than you might think and surprisingly hard to detect if you're not specifically looking for it.

Very good thought. I shall investigate ASAP.

[ricebridge]

Originally Posted by SD1too

Jonathan, can you specify what you mean by the left side of the engine please? On a transverse V6 this is the outer side of the left hand bank facing the radiator, but many people stand at the open bonnet and use the engine bay geography to describe it.

Sorry. Left side of the CAR. When seen from the driver's position. My bad.

Originally Posted by SD1too

Is that definitely coolant, i.e. is antifreeze residue present when dry? Is it happening repeatedly?

Yes. Every time.

Originally Posted by SD1too

What's the maximum coolant temperature now when the engine is under load?

That could be condensation in the exhaust being heated to vapour.

Simon

Works fine as long as there is coolant left. Working temp remains stable for some 10-20 kms (using onboard computer now). Then, you can see it starting to creep upwards, and when you check it afterwards, the coolant's gone. Every sign of a leak.